Calculate the quantity (in mmol) of protons that will be released when 2.80 mmol of oxygen bind to deoxyhemoglobin at ph 7.4 and the ph then returns to 7.4, i. e. in going from point a to point b on the curve. step 1: calculate the [hhb]/[hb] ratio at ph 7.4. step 2: calculate the mmol of hhb in 2.80 mmol of deoxyhemoglobin at ph 7.4. step 3: calculate the [hhbo2]/[hbo2] ratio at ph 7.4. step 4: calculate the mmol of hhbo2 in 2.80 mmol of oxyhemoglobin at ph 7.4. step 5: calculate the protons released as the difference between nhhb and nhhbo2.